CCNA IP Routing Practice Question
Exhibit
R1# show running-config | section ipv6
ipv6 unicast-routing
!
interface GigabitEthernet0/0
ipv6 address 2001:db8:acad:1::1/64
no shutdown
!
interface Loopback0
ipv6 address 2001:db8:acad:1::100/64
no shutdown
!
end
R1# show ipv6 interface brief
GigabitEthernet0/0 [up/up]
FE80::1
2001:db8:acad:1::1
Loopback0 [up/up]
FE80::100
2001:db8:acad:1::100You are connected to R1 via console. R1 and R2 are directly connected via their GigabitEthernet0/0 interfaces. Configure OSPFv3 for IPv6 on both routers so that the loopback0 interface on R2 (with IPv6 address 2001:db8:acad:2::1/64) is reachable from R1. Enable IPv6 unicast routing, enable OSPFv3 on the appropriate interfaces, and verify the neighbor adjacency and routing table. (Note: R2 already has OSPFv3 configured and is waiting for R1 to complete its configuration.)
⚠ Common exam trap
A common trap is confusing OSPFv2 and OSPFv3. Remember that OSPFv3 is for IPv6 and requires a router-id. Also, do not skip verification steps; they are often required in exam scenarios.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable IPv6 unicast routing, configure OSPFv3 process with router-id, enable OSPFv3 on GigabitEthernet0/0 in area 0, and verify neighbor and route.
The issue is that OSPFv3 process is not enabled on R1. To fix, first ensure IPv6 unicast routing is enabled (already done). Then configure OSPFv3 routing process with a process ID (e.g., 1) and router-id using the `ipv6 router ospf 1` command and `router-id` command. Then enable OSPFv3 on the GigabitEthernet0/0 interface with `ipv6 ospf 1 area 0`. Finally, verify with `show ospfv3 neighbor` to see R2's router ID (e.g., 2.2.2.2) and `show ipv6 route ospf` to see the route to 2001:db8:acad:2::/64.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable IPv6 unicast routing, configure OSPFv3 process with router-id, enable OSPFv3 on GigabitEthernet0/0 in area 0, and verify neighbor and route.
Why this is correct
This sequence is correct because OSPFv3 for IPv6 requires the global command 'ipv6 unicast-routing' to enable IPv6 on the router, an OSPFv3 process configured with a mandatory router-id (e.g., 'router-id 1.1.1.1') that uniquely identifies the router during adjacency formation, and interface-level activation using 'ipv6 ospf <process-id> area 0' on GigabitEthernet0/0. The final verification steps—'show ipv6 ospf neighbor' and 'show ipv6 route ospf'—confirm that the adjacency is up and IPv6 routes are being learned, which is the ultimate goal of the configuration.
- ✗
Enable IPv6 unicast routing, configure OSPFv2 process with router-id, enable OSPFv2 on GigabitEthernet0/0 in area 0, and verify neighbor and route.
Why it's wrong here
This option is incorrect because OSPFv2 is explicitly designed for IPv4 routing and uses IPv4 addresses to build LSAs and adjacencies; it cannot carry IPv6 prefix information. Since the requirement is to route IPv6 traffic, OSPFv3 is the correct protocol, as it supports IPv6 address families and runs natively over IPv6. Enabling OSPFv2 would leave the IPv6 routing table empty and no IPv6 neighbors would form.
- ✗
Enable IPv6 unicast routing, configure OSPFv3 process without a router-id, enable OSPFv3 on GigabitEthernet0/0 in area 0, and verify neighbor and route.
Why it's wrong here
The critical flaw here is omitting the router-id for OSPFv3. In OSPFv3, the router-id is a 32-bit value that must be explicitly configured because OSPFv3 does not use IPv6 addresses to identify routers—unlike OSPFv2, which can derive a router-id from IPv4 interfaces. Without a manually assigned router-id, the OSPFv3 process will default to 0.0.0.0, and the router will be unable to establish neighbor adjacencies, so no routes will ever be exchanged.
- ✗
Enable IPv6 unicast routing, configure OSPFv3 process with router-id, enable OSPFv3 on GigabitEthernet0/0 in area 0, but do not verify neighbor or route.
Why it's wrong here
This option incorrectly omits the verification phase. After configuring OSPFv3, it is essential to check that neighbor adjacencies have formed using 'show ipv6 ospf neighbor' and that IPv6 routes are installed using 'show ipv6 route ospf'; without these checks, the task is incomplete. The question explicitly asks to verify the neighbor and route, so skipping verification means the configuration has not been validated and potential issues like incorrect area assignment or interface misconfiguration would go undetected.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Enable IPv6 unicast routing, configure OSPFv3 process with router-id, enable OSPFv3 on GigabitEthernet0/0 in area 0, and verify neighbor and route.Correct answer▾
Why this is correct
This sequence is correct because OSPFv3 for IPv6 requires the global command 'ipv6 unicast-routing' to enable IPv6 on the router, an OSPFv3 process configured with a mandatory router-id (e.g., 'router-id 1.1.1.1') that uniquely identifies the router during adjacency formation, and interface-level activation using 'ipv6 ospf <process-id> area 0' on GigabitEthernet0/0. The final verification steps—'show ipv6 ospf neighbor' and 'show ipv6 route ospf'—confirm that the adjacency is up and IPv6 routes are being learned, which is the ultimate goal of the configuration.
✗Enable IPv6 unicast routing, configure OSPFv2 process with router-id, enable OSPFv2 on GigabitEthernet0/0 in area 0, and verify neighbor and route.Wrong answer — click to see why▾
Why this is wrong here
OSPFv2 supports only IPv4; OSPFv3 is required for IPv6 routing.
Why candidates choose this
Candidates may confuse OSPFv2 and OSPFv3, especially if they are more familiar with IPv4 OSPF configuration.
✗Enable IPv6 unicast routing, configure OSPFv3 process without a router-id, enable OSPFv3 on GigabitEthernet0/0 in area 0, and verify neighbor and route.Wrong answer — click to see why▾
Why this is wrong here
OSPFv3 uses a 32-bit router-id, which must be manually configured or derived from an IPv4 address; without it, the process cannot operate.
Why candidates choose this
Candidates may think OSPFv3 can use IPv6 addresses as router-ids, but it still requires a router-id in dotted-decimal format.
✗Enable IPv6 unicast routing, configure OSPFv3 process with router-id, enable OSPFv3 on GigabitEthernet0/0 in area 0, but do not verify neighbor or route.Wrong answer — click to see why▾
Why this is wrong here
Verification commands like 'show ospfv3 neighbor' and 'show ipv6 route ospf' are necessary to ensure OSPFv3 is functioning correctly.
Why candidates choose this
Candidates may focus only on configuration steps and overlook the verification step, which is a common exam requirement.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
OSPFv3 Single-Area Configuration for IPv6
Key term
IPv6
IPv6 is the most recent version of the Internet Protocol, designed to replace IPv4 by providing a vastly larger number of unique addresses and improved network features.
Key term
IPv6 address
An IPv6 address is a 128-bit numeric label used to identify a device on an Internet Protocol network, designed to replace IPv4 due to the exhaustion of available addresses.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.